Test: Ionization of Acids and Bases - ACT MCQ

The correct order of increase in acidic strength is HF ≪ HCl ≪ HBr ≪ HI. There are many factors affecting acid strength. Hear the hydrogen-acid Bond strength decreases, as the acid strength increases.

pH is defined as the negative logarithm of hydrogen ion concentration that is pH = -log[H⁺]. So here, the pH of the solution of sulphuric acid is -log[H⁺], where concentration of hydrogen ion is 0.01M = -log[10^-2] = 2.

The hydrolysis constant of a weak acid and weak base is K_W/K_aK_b, the degree of hydrolysis is √K_W/K_aK_b and the pH of the solution is given by 1/2pK_W + 1/2pK_a – 1/2pK_b. An example of a salt of a weak acid and a weak base is CH₃COOHNH₄.

Salts are strong electrolytes and on dissolution in water split up into ions. Which react with hydrogen ions are Hydroxide ions furnished by water yielding an acidic or basic solution. This process is called salt hydrolysis and is the reverse process of neutralization.

Salts are the products of the reaction between an acid and a base, these type of reactions are called neutralization reactions. There are many types of salts like normal, acidic, basic, double, complex and mixed salts.

We know that the ionization constant of water at 298 k is given by [H₃O⁺][OH^–] = 1 x 10^-14/mol²L². pK_W = pH + pOH = -log[H₃O⁺] – log[OH^–] = -log[H₃O⁺][OH^–] = -log10^-14 = log10¹⁴ = 14. Therefore pK_W at 298 k is 14.

Ionic product is a product of the concentration of hydronium ions and hydroxyl ions in pure water, which remains constant at a particular temperature. It is symbolized as K_W and is equal to 1 x 10^-14/mol²L².

We know that the pH of the solution of a weak acid and a weak base is given by 1/2pK_W + 1/2pK_a – 1/2pK_b. So pH = 7 + 12[4.2 – 3.24]; pH = 7 + 0.48 = 7.48, we get this by substituting acetic acid’s pK_a as 4.2 and ammonium hydroxide pK_b as 3.24.

The dissociation constant K = [H⁺][HCOO^–]/[HCOOH] = x²/0.1 – x = 1.77 x 10^-4; x = [H⁺] = 0.0042M. The percent of dissociation is x/0.1 = (0.042M)100% = 4.2. Therefore the value of degree of dissociation is 4.2

The aqueous solution of a salt of a weak acid and strong base is alkaline, due to the anionic hydrolysis and aqueous solution of a salt of a strong acid and weak base is acidic, due to cationic hydrolysis with dilution degree of hydrolysis increases.

Normal salts like NaCl are obtained by complete neutralization of an acid with a base. Acidic salts are formed by incomplete neutralization of polybasic acids and basic salts are formed by incomplete neutralization of poly acidic base. Double salts are formed by the combination of two simple salts and exist only in the solid state.

Acids always have a pH below 7 and bases have a pH of above 7, while neutral compounds have a pH of 7. Here gastric juice, vinegar, and lemon are acids, so they have a pH of below 7, but blood plasma is a base. It has a pH greater than 7.

pH is defined as the negative logarithm of hydrogen ion concentration that is pH = -log[H⁺]. By rearranging pH in terms of concentration of hydrogen ions, we get [H⁺] = 10^-pH. pH means potential of hydrogen.

Concept:
​Basicity of a compound-

• It is the ability of a compound to donate its pair of electrons.

The basicity of a compound depends on the-

• The less electronegative element has greater basicity due to the low attraction of electrons.
• The compound having a negative charge will have a greater ability to donate electrons and higher will be the basicity.
• Compounds with positive charges will not be willing to give up electrons and will be the least basic.
• Molecules, where the electron pair is delocalized by resonance, will be less basic.
• Compounds, where more than one donor centres are present, will be highly basic.

Explanation:

• In decreasing order of basicity is LiCH₃ > LiNH₂ > LiOH > LiF.
• The ions, F⁻, OH⁻, NH₂⁻ and CH₃⁻ are stable ions compared to their conjugate acid.

 List of Acid and Natural Resources: